Dokument: Electron acceleration in relativistic laser-matter interaction
| Titel: | Electron acceleration in relativistic laser-matter interaction | |||||||
| Weiterer Titel: | Elektronenbeschleunigung durch relativistische Laser-Materie-Wechswelwirkung | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=8263 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20080714-112709-7 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | Seredov, Vasily [Autor] | |||||||
| Dateien: |
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| Beitragende: | Prof. Dr. Pukhov, Alexander [Gutachter] Prof. Dr. Pretzler, Georg [Gutachter] | |||||||
| Dewey Dezimal-Klassifikation: | 500 Naturwissenschaften und Mathematik » 530 Physik | |||||||
| Beschreibung: | The acceleration of charged particles is one of the fundamental problems in high energy physics. The conventional
accelerator technology has nearly reached its natural limit because the maximum available electric field is bounded by destruction of the accelerating structures. This fundamental limit on the electric field leads to the monstrous sizes of the modern accelerators. The main advantage of plasma based accelerators is the possibility to increase the electric field and consequently the accelerating rate by several orders of magnitude compared to the conventional technology. One of the most promising ways to employ the plasma acceleration is to use high intensity ultra-short laser pulses to excite the plasma wake field. The physics of relativistic laser plasma is highly nonlinear and requires extensive multi-dimensional computer simulations. The present work is dedicated mainly to the problem of electron acceleration in the so-called "bubble" regime. The advantage of the bubble regime is the possibility to generate quasi-monoenergetic electron bunches. The bubble regime was first discovered in three dimensional particle-in-cell (PIC) simulations. Recently, it was observed in a number of laser-plasma experiments. One of the central questions in the physics of the bubble is the problem of particle trapping and trajectories of the relativistic electrons during the acceleration stage. Because the bubble structure has not only the longitudinal - accelerating - electric field, but also transverse fields, the electrons runs at curved trajectories and emit strong betatron radiation in x-ray range. The angular distribution of these x-rays allows to draw conclusions on the particle trajectories. In this work, a simplified analytic description of particle trajectories in the bubble fields is suggested. Further, the bubble is simulated using the 3D PIC code VLPL (Virtual Laser Plasma Laboratory). The code VLPL has been further developed to allow individual marking for each particle. Thus, trajectories of individual particles trapped in the bubble can be traced over the full interaction length. A simulation done for realistic laser-plasma parameters has shown a reasonable agreement between the simplified theory and the simulations. It is shown that in some cases the electron trajectories have the form of a helix around the axis of the laser pulse propagation. In addition, we have stored initial positions of all the trapped particles. This analysis revealed that the electron trapping in the bubble is not steady, but rather contains striations. We have discussed the capture of electrons in the bubble for linear and circular polarization cases. It was shown that the shape of the area of electrons capture directly depends on the laser pulse polarization. Finally, the new analytic model for an ultra-short laser beam has been developed. Although there is a well-known model for an infinite focused laser pulse, it becomes inexact when applied to an ultra-short laser. The reason is that the ultra-short pulse contains many frequencies. The analytic model has been implemented in the VLPL3D code and used to study dependence of electron acceleration by an ultra-short laser pulse as a function of the focal position in plasma. | |||||||
| Lizenz: |  Urheberrechtsschutz | |||||||
| Fachbereich / Einrichtung: | Mathematisch- Naturwissenschaftliche Fakultät » WE Physik » Theoretische Physik | |||||||
| Dokument erstellt am: | 08.07.2008 | |||||||
| Dateien geändert am: | 08.07.2008 | |||||||
| Promotionsantrag am: | 27.05.2008 | |||||||
| Datum der Promotion: | 17.06.2008 |
